Spanish Civil War - Polish PZL Fighters

[apophenia]

This story was prompted by an thread on Secret Projects called 'Alternate Spanish Civil War Aviatioń. I have not followed the exact discussion in the SPF thread but it was definitively an inspiration.

-- https://www.secretprojects.co.uk/threads/alternate-spanish-civil-war-aviation.51976/

I've tried to address the RW political and industrial impediments to Poland providing combat aircraft to Republican Spain. In my what-if, those considerations dictate the creation of new PZL sub-types. The urgency of fighting in Spain will also push the development of a (hopefully plausible) what-if interim fighter for Poland's future.

Apologies in advance to any Spanish- or Polish-speakers for any manglings of their languages in my text. Doubltess such errors are annoying but they were unintentional. Any corrections (to spelling or idiom) are most welcome.

Enjoy ... but brickbats and suggested alternatives are also welcome.

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Polish Gull-Winged 'Gaviotas' in Spain (Part 1)

In Oct 1935, a Memorando de Entendimiento was signed between the governments of Republican Spain and Poland. Warsaw committed to supplying 36 x PZL P.11 fighter aircraft. The Poles also agreed to the immediate supply 28 x used PZL P.7s to act as advanced fighter-trainers. These P.7s would be officially on loan to Spain to get around an export ban on the type's Skoda-made Bristol Jupiter engines. [1]

In early Dec 1935, the first shipment of eight PZL P.7a fighters arrived by sea at the port of Cádiz in the south of Spain. There, Construcciones Aeronáuticas S.A. took responsibility for the re-assembly of the Polish airframes. After acceptance by Aviación Militar inspectors at CASA Cádiz, completed P.7s were flown to Getafe for use by the Escuela de Vuelo y Combate or distribution amongst the former Nieuport units of Grupo 11. More partially disassembled P.7a airframes would follow.

With the outbreak of the civil war, the P.7s quickly became one of the Republic's top performing fighter types. Two Escuadrillas Mixtas were formed - one at Málaga, the other at Cádiz. Málaga's 1ª Escuadrilla Mixta de PZL P.7 y Ni-H.52 was equipped with aircraft flown south from Getafe while Cádiz-based 2º EM collected its PZLs directly from the CASA works. It would be Escuadrilla Mixta de PZL P.7 y Ni-H.52 at Cádiz which would bear the brunt of initial 'Nationalist' aerial efforts launched from Morocco.

PZLs Into Combat - the Cauldron of Cádiz

The revolt of the Ejército's Cádiz garrison began on 18 July. As a result, 2º EM  found itself isolated and surrounded on the Aeródromo de Cádiz. A division of labour was agreed whereby the squadrońs Nieuport biplanes would focus on the attack role to secure the airfield while the faster PZLs would engage the rebel transport and bomber aircraft. Success was immediate when a trio of P.7s intercepted a flight of 'Nationalist' Fokker F.VII transports over the Gulf of Cádiz on 18 June.

Upon interception, one of the F.VIIs pitched into a steep dive and was not seen again. [2] Of the remaining three Fokkers, two were claimed as damaged and the third was shot down into the sea by cabo Alonso Santamaría. The damaged  F.VIIs turned tail for Morocco, one trailing smoke as it left. With the 'Nationalist' aerial troop transfer thwarted for now, the Spanish PZLs had been 'blooded'.

In an effort to secure their aerial lifeline to Morocco, the 'Nationalists' moved a flight of Breguet Bre.XIX light bombers to Aeródromo de Jerez just 100 km north of Cádiz. The intended continuous bombing and harassment of the Aeródromo de Cádiz proved impossible. The PZL flight quickly got the measure of the Breguets - cabo Santamaría having previously crewed on the type. In the end, only dawn and dusk raids by the Breguets were survivable.

Top A PZL P.7a 'Gaviota' of 2º Escuadrilla Mixta de PZL P.7 y Ni-H.52 based at the Aeródromo de Cádiz. This Skoda Jupiter-powered fighter is armed with twin 7.7 mm Vickers E machine guns. The scheme is the original Polish khaki wczesny overpainted with verde medio.

With no time to establish a unit emblem, the skull-and-cross-bones marking on CG-19 was presumably concocted by the ground crew. All 2º EM aircraft were shared amongst available pilots. Thus, the 'kill' markings on the tailfin represent a Breguet each knocked down by cabo Santamaría and sargento Muñoz as well as Santamaría's Fokker F.VII claim.

The over-worked Nieuports of 2º EM added strafing runs on Jerez de la Frontera to their repertoire. The cost on 2º EM aircraft and pilots was high but the Jerez field was left strewn with burnt-out Breguet biplanes. However, the deployment to Jerez had served its purpose. Thus distracted, 2º Escuadrilla Mixta de PZL P.7 y Ni-H.52 were unable to mount the standing patrols needed to intercept fascist transport aircraft heading for Sevilla. The 'Nationalists' were forming a critical mass in the south.

By the beginning of August, continued operations from Aeródromo de Cádiz had become non-viable. On the evening of Sunday, 02 August, the remaining flight-worthy aircraft were flown out carrying as many ground crew and other personnel as could be carried. Depending upon personal choice, the remaining defenders would surrender, fight to the last, or slip away in an attempt to join the local resistencia.

PZL P.7a - Del Cazador al Asalto

With the appearance of the PZL P.11s in Spain, the lower-powered P.7s could begin to replace worn-out Nieuport H.52 (aka NiD.52) biplanes in the low-level assault role. Initially, no P.7a airframe changes were made. However, Poland was also surreptitiously supplying Spain with replacement P.7s to make up for combat losses. These 'P.7h' replacements - with 'h' for hiszpański - were slightly refurbished Polish air force P.7a airframes which also featured a new belly bomb rack for level bombing (this rack stopped the main fuel tank from being jettisonable but that capability could be restored with the belly rack removed; eg: with light grenade-bombs carried on the wing racks in place of a belly bomb).

The 'P.7h' was announced as a 'new' model powered by a 480 hp Gnome-Rhône 9Ab Jupiter engine. In reality, all 'P.7h' retained their original Skoda-made Jupiters - the mention of fictitious 'Gnome-Rhônes' to simply a dodge to get around Bristol's renewed insistence on no exports for Polish-made engines of its design. [3]

The first tranche of 16 x PZL 'P.7h' attack-fighters arrived at Bilbao in Nov 1936. The main change was the previously-mentioned belly bomb rack. The 'P.7h' was also armed with twin, synchronised Vickers E guns which had been bored out and converted for 7.9 mm rounds (simplifying Spanish ammunition supplies). The 'P.7h' also adopted the small armour plates devised in Spain to offer pilots a bit more protection from ground fire.

Bottom A PZL 'P.7h' Gaviota flown by sargento Jesús García Herguido of the 21º Escuadrilla de Asalto (Internacionales) on the Aragon front. Based at the Aeródromo de Sariñena, 21º EdA(I) mainly performed strafing and bombing attacks on the 'Nationalist' defenders of the surrounded city of Huesca.

The scheme for CG-63 is the original Polish khaki wczesny overpainted with a locally-mixed equivalent to verde medio. Red ID panels have replaced the Republican roundels. On the fuselage side is the 21º EdA(I) mascot. [4] Gaviota CG-63 would be lost on Christmas Day 1936 - downed by ground fire from hilltop positions around rebel-occupied Huesca.

The shift of Republican P.7s to the attack role reinforced the fact that the earlier PZL fighters were now being outshone by the more manoeuvrable Italian Fiat C.R.32 biplanes. This performance gap led to a quickening of the PZL P.11 procurement programme.

(To be continued ...)

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[1] The British engine-maker had become slightly more flexible on 'foreign use' of the obsolescing Skoda-built Jupiter radials. However, Bristol remained adamant about banning exports of the more modern, Polish-made Mercury engine.

[2] That Fokker F.VII crew and their terrified Moroccan passengers had survived the extreme dive and flown on to land at Sevilla. The aircraft itself, however, took a beating - suffering structural damage to both wing skins and engine support struts brought about by the high-G pull-out over the Golfo de Cádiz.

[3] The change in Bristol Aeroplane Company's attitude was related to the British government signing the 1936 Non-Intervention Agreement regarding the Spanish Civil War.

[4] Chosen by Polish volunteers to the 21º EdA(I), this silly billy goat is, of course, the Polish cartoon character Koziołek Matołek. As a mascot, Koziołek Matołek is doing his bit by dropping 'bombs' on the fascists.

[apophenia]

Polish Gull-Winged 'Gaviotas' in Spain (Part 2)

Before the first shots were fired in the Spanish Civil War, the first P.11c fighters allocated to Madrid's order were progressing down the PZL WP-1 production line in Okęcie. In light of Bristol's no-export licensing condition, these aircraft were powered by imported Mercury engines built by Bristol at their Filton plant. This plan worked well until a Non-Intervention Committee was established in London in Sept 1936. Thereafter, the supply of Filton-built engines dried up.

At that point, Spain had only been supplied with a dozen P.11c fighters out of the 36 ordered. Unwilling to risk Bristol's (or Londońs) rath, Warsaw ordered PZL to source a new engine type. Fortunately, the first Gnome-Rhône powered P.11f for Romania had just been prototyped. It was, thereforę decided that the remaining 24 x PZL fighters for Spain would be fitted with 610 hp Gnome-Rhône 9Krse radials. [4]

Enter el Halcón - The PZL P.11h

The P.11f derivatives to complete the remainder of the Republican order were designated P.11h (for hiszpański or hispana) by PZL. In Spain, G-R 9K-powered P.11s were considered tramo 2 (or tranche 2) - tramo 1 being the Mercury-powered P.11c fighters originally ordered. But, in the field, the P.11h fighters were dubbed Halcón (Hawk) ... although, like all PZLs, they were just as apt to be called la polaca in Spain.

The camouflage scheme specified for Spanish P.11 fighters had been verde bosque (forest green) over azul cielo (sky blue). This proved too dark for most Spanish operating environments and blotches of tan or brown paint were often applied in the field to tone the scheme down.

Top: A wireless-equipped P.11h fighter of 1ª Escuadrilla de Halcones based at Alcalá de Henares for the aerial defence of Madrid in Nov 1936. P.11h CH-33 'Dominó' was flown by capitán 'Rojo García' - a nom de guerre for the jefe de sección (section leader) of 1ª EdH.

At this early stagę the Halcones retained Spanish Republican roundels (although the wing roundels have already been overpainted with largę quickly-recognised red ID panels extending out to cover the wingtips. The domino emblem of 1ª EdH is worn on its tail fin of CH-33 - the 33rd Caza tipo Halcón. [5]

Early on, the Spanish found it necessary to restrict Darne machine gun issuance for the tramo 2 P.11h fighters. [6] Although unfortunatę a silver lining was the realisation that twin-gunned PZLs climbed more quickly than their 'fully armed' wing mates. This resulted in aircraft with 2 x guns being detailed to  operate as pure fighters while the 4-gunned fighters specialised in bomber interception. As a result, Madrid requested that further P.11h fighter production be alternated between 4-gun and twin-gun fittings.

Bottom: A P.11h fighter (CH-91) of an entirely Polish-manned volunteer unit - the 3ª Escuadrilla de Caza (Internacionales) - in early 1937. This is a twin-gunned tramo 2 aircraft. Note the new red recognition panels (applied in Spain) and the 'folded bird' emblem favoured by 3ª EdC(I).

The revised camouflage specified for tramo 2 aircraft consisting of a paler oliva oscuro (dark olive) and marrón medio (medium brown) pattern over the azul cielo undersides. CH-91 would be lost in combat with a trio of fascist C.R.32s over Trijueque in the Guadalajara area in late March of 1937.

While P.11h Halcones fought for Republican Spain, the design department of PZL had not been resting upon its laurels. The French engine-maker Gnome et Rhône had offered PZL 150,000 francs in development funds and a free prototype engine to evolve an export-suitable P.11 powered by its twin-row Gnome-Rhône 14K engine. That concept had emerged as the P.11a-based P.24/I prototype back in 1933. By June 1934, the P.24/II had established a new FAI speed record for radial-engined fighters.

PZL had a world-beater on its hands and the P.11c-based P.24 production series would turn out to be a good little money-earner for Poland. Orders came in from Turkey, Greecę and Bulgaria with production licenses then bought by both Turkey and Romania. It was anticipated that these P.24 earnings would soon be followed by more Spanish gold.

(To be continued ...)

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[4] The 'fix' was not quite as simple as it sounds. Another 13 x P.11c airframes for Spain had reached an advanced state on the Okęcie line. These fighters were to be redirected to Poland's Lotnictwo Wojskowe (six fitted with Filton-made engines, seven with PZL-built Mercurys). Their replacements for Spain would be added to the Gnome-Rhône engined variants.

[5] These individual aircraft codes were applied based on an airframes arrival in Spain. Thus, CH-33 would be the 33rd P.11 type (CH-01 to CH-12 being P.11c types) and the 21st P.11h sub-type.

[6] The Republican government had arranged to source locally-made Darne guns (produced by Unceta y Cia SA of Guernica under the Astra brand name). Initially, however, deliveries were deliberately slowed by a Nationalist-leaning Unceta y Cia management.

[apophenia]

Polish Gull-Winged 'Gaviotas' in Spain (Part 3)

By the end of the Summer of 1936, 'Nationalist' gains against Republican Spain were becoming alarming. Fascist Italy and Nazi Germany made little attempt to hide their flouting of the 1936 Non-Intervention Agreement which they had just signed. With such blatant acts as the establishment of the Aviazione Legionaria and the Condor Legion, effective Italian and German support for Franco's rebels was growing. In studying the situation, officials of Poland's Lotnictwo Wojskowe decided to act in kind.

There would be no Polish 'Lotnictwo Legionowe' formed in Spain. Rather, volunteers would be sought from among experienced air crew and maintainers serving with the Lotnictwo Wojskowe. Temporary leaves would be granted and positive career growth guaranteed. At first, the response was sluggish. Even amongst the podoficerowie (NCO pilots), there was little ideological sympathy with Republican Spain. Still less amongst the officer class. An indirect approach was required.

Warsaw had secretly promised Madrid at least one volunteer fighter squadron. To clinch the deal, Madrid guaranteed that such a squadron would be assigned to the front directly opposite the new Condor Legion - guaranteeing Polish pilots a crack at the Germans. It turned out that conservative, Catholic Poles wereńt keen on Spaińs 'godless' socialists ... but they despised Nazis even more. Suddenly, the Lotnictwo Wojskowe faced a new challenge of having too many service personnel requesting leave as volunteers!

Along with the first PZL P.11s sent to Spain went engineering personnel from the Korpus Oficerów Lotnictwa - Grupa Techniczna (or Aviation Officers Corps - Technical Group). The foremost role of the KOL-GT was to oversee maintenance and ensure spares. But their secondary role of gathering technical intelligence had begun to grow in importance.

The KOL-GT prepared technical reports on enemy types (German and Italian) in-theatre but, more quietly, it also reported on Republican types which had been supplied by the Soviet Union. The latter reports were originally dominated by the Tupolev SB medium bombers. With a speed of 244 mph at 4,000 m, the SB 2M-100 was the match of any P.11 fighter. [7] And even faster SB 2M-100As were now showing up in Spain.

Another nasty surprise for the Lotnictwo Wojskowe was the KOL-GT's assessment of Soviet Polikarpov I-16 fighters. When the portly Polikarpov low-winged monoplane was first displayed in the west - in Milan at the Oct 1935 1° Salone internazionale aeronautico - most western commentators remarked upon poor Soviet workmanship. In Spain, however, the 'Mosca' was quickly developed a solid reputation. Unlike Soviet biplane fighters, the I-16 matched PZL P.11h performance in most categories. The I-16's climb rate was slightly inferior but 'Mosca' was a full 65 mph faster at altitude than the P.11h.

¡Cuidado con el Huno en el sol!

If the Soviet Polikarpov I-16 came as a nasty shock, a new low-winged monoplane fighter from Nazi Germany was almost paralysing. The Messerschmitt Bf 109B-1 began showing up in Spain in March 1937. They served in the Condor Legiońs Versuchsjagdgruppe 88 and soon engaged in aerial combat with Polikarpov I-16s. While the latter still had some game (and the numbers for now), the new German fighter was obviously the future.

The Messerschmitt's compact airframe was as structurally advanced now as the PZL gull-wing had been when first introduced back in 1929. The Bf 109B-1 clearly outclassed the much-vaunted I-16 but suffered none of that stubby Soviet fighter's handling dangers. On little more than the power available to a P.11c, the Bf 109B-1 was already 55 mph faster than the PZL. The German monoplane was shorter-ranged but had a faster rate of climb. In the air, the Bf 109B-1 couldńt be touched and Messerschmitt was already developing even more powerful and better-armed derivatives.

To say that KOL-GT reports on Polikarpov and Messerschmitt fighters precipitated a crisis of confidence within the LW's Słuz[.]ba Lotniczo-Techniczna (Aviation-Technical Service) would be an understatement. State-owned PZL had been focused on generating cash income for Warsaw through successful export sales of the P.24 series of fighters. But Lotnictwo Wojskowe planners had also leaned towards developing a 'domestic' P.24 variant to replace their aging P.11c fleet.

Kryzys zaufania - No PZL P.24h for Spain

The Komitetu ds. Uzbrojenia i Sprzętu (Committee for Armaments and Equipment) had recommended the commissioning of a 'P.24PL'. The goal was a common airframe to arm both the Lotnictwo Wojskowe and the Fuerzas Aéreas de la República Española. Both fighter types would be powered by the subsidised Gnome-Rhône 14K (or its Romanian-licensed) IAR K14 equivalent. As soon as possiblę production would shift to the better-cooled Gnome-Rhône 14N radials (to be license-built at the former Skoda works by PZL WS-1).

The generalised 'P.24PL' and Spaińs P.24h began to diverge. But arguments in the Warsaw planning offices of the Dowództwo Lotnictwa (Air Force Command) over the ideal armaments for these new fighters became moot. The 'P.24PL' might have been better-armed and more powerful than a P.11c or P.11h but the new fighter would only be 10 mph faster. In other words, a 'P.24PL' had no more chance of successfully intercepting a Soviet SB or catching a Nazi Messerschmitt than did an in-service P.11c or P.11h.

Top: This never happened. The PZL P.24 was the logicial successor to the P.11h. But, by the time a P.24h Halcón II design was finalised and space was available on the line at Okęcię the era of such gull-winged fighters had passed.

Both the planned 'P.24PL' for Poland and P.24h for Spain were cancelled outright. The latter would be replaced immediately by further shipments of P.11s. These ex-Lotnictwo Wojskowe P.11c fighters would be listed as P.11h/IIs (with the false implication that they were IAR- or Gnome-Rhône powered). That dodge was to satisfy British restrictions on exports of Polish-made engines. Of coursę Bristol knew exactly what the Poles and Spaniards were up to but Filton had been placated through access to secret Polish data on the performance of Mercury engines during extended combat exposure.

Bottom: Una falsificación - an ex-Lotnictwo Wojskowe PZL P.11c masquerading as a P.11h Halcón. Such sucedáneo 'P.11h/II' were issued to various Escuadrillas  de Halcones (Internacionales). The unit here remains unidentified but it may well have been American-manned (based on the Texas-like motif on the rear fuselage).

The scheme is the original P.11c khaki with all Polish 'szachownice' ('chess board' national emblems) and other areas overpainted with two tones of oliwka. Republican red ID panels have been added but, for reasons unknown, CH-106 never received its FARE rudder stripes.

(To be continued ...)

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[7] Making the chances of current LW fighters successfully intercepting Soviet V-VS bombers very slim indeed. Back in Warsaw, the KOL-GT was also well aware of the latest model SB 2M-103s establishing altitude records and quite capable of showing any P.11 a clean pair of heels.

[apophenia]

"Everything else is credit" - New PZLs in Spain (Part 4)

The proposed 'P.24PL' variant had never been anything but an interim solution.
Spanish gold reserves had secured gull-winged PZL fighters for the Republic. Now that same gold - along with P.24 export profits - would help finance development of the next generation of Polish fighters. These more modern fighters would take part in the final defence of Catalonia ... and then they would help defend Warsaw from the Luftwaffe.

Replacing the 'P.24PL' in established Lotnictwo Wojskowe planning was the advanced, low-winged PZL.50 Jastrząb (Hawk). The P.11c was obsolescing quickly but, by contrast, progress on the Jastrząb was positively glacial. PZL's chief designer, inż Wsiewołod Jakimiuk, had been held up on completing the PZL.50 by oft-changing engine choices and delayed delivery of a retractable undercarriage sourced from Dowty in the UK. With no sign that a Jastrząb prototype would be completed before 1939, an 'interim-interim' solution was needed.

Thus, it was with something of a panic that PZL engineers Franciszek Misztal and Jerzy Dąbrowski were re-assigned to the task of producing a competitive low-winged monoplane fighter as rapidly as possible. Baked-in as a priority was the need to evolve this new fighter from the maximum possible P.11/P.24 components in order to speed both the design process and production. Like all new Polish military aircraft, this fighter was assigned a 'popular' name - Krogulec (or Sparrowhawk).

Price of Progress - A Partly New Iron in the Fire

Ultimately, the new fighter aircraft would be designated PZL P.51 - although, to be fair, that 'P' was a misnomer. Although the brief was to incorporate as many P.11c and P.24 components as was practical into the P.51, there was little or nothing left of Zygmunt Puławski's original 1931 PZL P.11/I design - either conceptually or materially. The rear fuselage was retained but, in reality, that refined P.11c structure had been designed by inż Jakimiuk after the death of Puławski.

In a division of labour, Franciszek Misztal was tasked with creating the wing for what became the P.51 while Jerzy Dąbrowski was to integrate the old fuselage into this new design. For speed, Misztal chose to incorporate the wing design from his PZL.38 Wilk - a stalled twin-engined fighter concept he had been working on. [8] The centre section of that 3-part wing was narrowed - giving a final span of 9.90 m (32.5 ft) and an area of 17.18 m2 (185 sq ft). The outer panels were also given more dihedral.

For simplicity, Misztal advocated a Seversky P-35 style main undercarriage. But, ultimately, that was Jerzy Dąbrowski's call ... and he chose a main gear designed by France's Société Messier instead. The legs of these units attached to the dihedral-less wing centre section while retracting outward to be housed in the outer wing panels. That made for much cleaner lines than the arrangement advocated for by Misztal. However, this outward-retracting main gear took up more wing 'real estate', adding complexity to fixed armament installations.

Prototypowanie - You've Gotta Start Somewhere

The first prototype PZL P.51/I 'recycled' a P.24G fuselage and was powered by a 920 hp IAR K14 radial enclosed within the same straight-sided cowling designed for the PZL P.24/III prototype. Since that engine type couldńt accommodate a synchronisation gear, all fixed armament was to be mounted in the wings. In this first prototype P.51, this consisted of twin 20 mm Oerlikon FF autocannons inboard of the wheels plus a pair of 7.92 mm PWU wz. 36 machine guns mounted outboard of those retracted wheels.

As developed into the production P.51H, the armament was revised to the same 4 x 7.9 mm Darne as Spanish P.11s . It was planned that this would, eventually, be changed to either 6 x 7.9 mm Darnes or a 4-gunned type with inboard 13.2 mm FN Browning heavy machine guns. In theory, a bomb pylon could be attached beneath the wing centre section although this was never done on operational P.51Hs. Officially, the handful of P.51Hs to arrive in Spain had been snuck through through the blockage into the port of Barcelona. But that was a ruse. In actuality, Gnome et Rhône had used its influence with the French government to have the P.51H airframes  delivered via Bordeaux. [9]

Scion of the P.11c - The PZL P.51A for Poland

Risking a jinx, the fuselage of a wrecked P.11c was the starting point for building the second prototype PZL P.51/II. The 640 hp Mercury VI S.2 from the P.11c was retained along with its fixed-pitch, wooden Szomanski propeller. Armament was 2 x synchronised 7.92 mm PWU wz. 36 machine guns with another pair of wz. 36 mounted in the new wings (inboard of the retracted main wheels). Both powerplant and armament would be changed for production examples.

A third prototype PZL P.51/III was prepared from another P.11c airframe. This would become the definitive engine and armaments prototype for the Lotnictwo Wojskowe's production model P.51A. In contrast to the P.51/II, the third prototype featured a Bristol-built Mercury VIII radial (albeit still driving a Szomanski prop) and was armed with twin synchronised Belgian 12.7 mm FN-Browning M2 HB guns. [10] After acceptance the P.51/III was allocated to Warsaw's Instytutu Technicznego Lotnictwa for further trials.

Production P.51As would be essentially similar to the third prototype but were powered by a 725 hp PZL-built Merkury VIII engine (with an emergency rating of 840 hp). As planned, the synchronised fuselage guns became PWU-FB built 12.7 mm ckm wz. 38 FNs licensed from FN Hestal in Belgium. [10] Along with those Radom-built ckm wz. 38 FN medium guns were the twin, wing-mounted PWU wz. 36 rifle-calibre machine guns which fired outside of the propeller arc.

Stado Krogulców - Proliferating P.51 Variants

Priority was given to developing the first two prototyped P.51 variants - producing the production model P.51H Gavilán for Spaińs FARE and the Merkury-engined P.51A for Poland. However, a number of proposed P.51 variants were also in the offing. These included P.51 offerings for existing P.24 export customers as well as for the Lotnictwo Wojskowe itself.

For Poland's defencę the most important of these variants was the PZL P.51C which was to be powered by a 1,050 hp Gnome-Rhône 14N-07 built by PZL WS-1 as the Gnom. The closely-related PZL P.51D was developed as a safety measure - effectively being a PZL P.51C which retained the P.51H's Romanian 920 hp IAR K14 engine. As it happened, neither of these Polish alternative models would be realised. Records will show 'P.51Dś in Polish service in Sept 1939 but, in reality, these were P.51H airframes completed for the Lotnictwo Wojskowe after the March 1939 collapse of the Spanish Republic.

Romania's IAR had sought a license for domestic production of the P.51F. This type also provided the model for a more general export type - the P.51E (Eksport) - which would, ultimately, be offered with a range of engine types and armament options. More specific proposals were the P.51K (Kayseri) to be built in Turkey (aka the 'P.51T' for Turcja or Türkiye) and the P.51G (Grecja) to replace Ellinikí Vasilikí Aeroporía P.24Gs. None of these variants were ever realised. [11]

The PZL P.51 'Sparrowhawkś Into Service

The first PZL P.51H Gavilán were delivered with 4 x 7.9 mm FN Browning guns. Indeed, once the collapse of the Catalonian front began in earnest, confusion reigned. It remains unknown whether any 6-gunned Gavilanes ever arrived in Catalonia during those dying days of the Spanish Republic. The low-winged PZLs gave the 'Nationalistś and their fascist allies a surprise but it was an obvious matter of too littlę too late. The Condor Legion and Aviazione Legionaria already soaked up the skies.

Top: A captured P.51H Gavilán after the end of the Spanish Civil War in the colours of Franco's Ejército del Aire (established in Oct 1939). This Gavilán, found relatively intact in Catalonią has been completely stripped of its original paintwork. This trophy P.51H was to be displayed in a flypast over the Paseo de la Castellana during Franco's grand 19 May 1939 victory parade.

Prior to repainting, a test flight was made by the intended display pilot, civil war ace alférez Arístides García. This flight was made without a replacement lower cowling having been located. After departing the Aeròdrome del Prat, the upper cowling was seen to part company with the airframe. The stricken P.51H came down in the Balearic Sea. The body of Arístides García López Rengel was never recovered. [12]

Compared with the P.11h the higher-powered P.51Hs were a much better match for early-model Bf 109s ... but the Messerschmitts still held an edge. Although less immediately urgent, this imbalance in performance was greatly concerning for Polish planners. If, as anticipated, war between Poland and Germany broke out in the Summer of 1940, the bulk of the Lotnictwo Wojskowe interceptor force would still be made up of Merkury-powered PZL P.51A Krogulce fighters (backed up by those P.11c 'Jedenaste' gull-wings which had not yet been converted for the ground attack role).

The Luftwaffe's latest Messerschmitt Bf 109E model was cannon-armed (which sounded more impressive than it was). Due to a low muzzle velocity, the Oerlikon MG-FF cannon had an effective range was only 100-400 meters (comparable to 185 to 365 m for the Darnes arming the P.51Hs). By contrast, the higher muzzle velocity 12.7 mm ckm wz. 38 FN guns arming the Polish P.51A Krogulec had an effective air range of 550 to 900 m. When synchronised, the 12.7 mm machine guńs rate of fire was little more than the Oerlikon. But a Polish pilot could always open fire first and from further away. [13]

In Warsaw, P.51 development continued at a frenzied pace. So too did schemes to develop even more potent Polish fighter aircraft. But as the Summer of 1939 approached, the rest of Europe slipped towards the fate already suffered by Republican Spain. A deadly game board had been set and the Lotnictwo Wojskowe would be forced to fight with the aeronautical chessmen already at its disposal.

Bottom: The prototype PZL P.51/III was originally assigned to the Instytutu Technicznego Lotnictwa in Warsaw. In late Aug 1939, this aircraft was sent to an operational unit - 114 Eskadry Myśliwskiej at Poniatow. The swallow (jaskółczy) emblem of 114 EM has been applied to the fuselage side (despite orders from Lotnictwo Wojskowe HQ that all such unit identifiers were to be eliminated from combat aircraft).

 During the retreat south, this aircraft was lost in aerial combat near Kozienice. The pilot, kpt inż Stanisław Dudziński - an ITL staffer - parachuted to safety. Note that the prototype PZL P.51/II retained the P.11's open cockpit, never receiving the canopy fitted to the production model P.51A Krogulec.

(Fin)

____________________________________

[8] In the end, the PZL-Wytwórnia Silników (engine factory) would kill off its Foka IV-8 powerplant. That signalled the end of the PZL.38 Wilk (the similarly-powered LWS-4 - aka PZL.39 - light fighter having already been cancelled).

[9] At Bordeaux, the PZL airframes were offloaded for assembly and fitted with their French-made Ratier 3-bladed constant-speed propellers.

[10] The Polish air force would have preferred the 13.2 mm FN Browning but could not afford to wait another year for that Hotchkiss-cartridged gun.

[11] Although no Romanian P.51F were ever built, the ARR did take two 'refugee' PZL P.51D/P.51H fighters into service in Oct 1939. Fortunately for the ARR, IAR had persisted with an alternative P.24E-based low-wing monoplane design of its own - the IAR 80 series which entered service in Feb 1941.

[12] The 'stripped' PZL P.51H in Nationalist' colours profile is based upon a photo of a beautifully-made IAR 80 model build in 1/72nd by Polish britmodeller.com member, Yawimaya.

[13] The Bf 109E's secondary armament were a pair of synchronised 7.92 mm MG 17 guns with an effective range of 200 to 400 meters.

[Frank3k]

This is great! How far do the red ID panels extend from the wingtip?

[apophenia]

This is great! How far do the red ID panels extend from the wingtip?

Thanks, Frank!

I hadn't really thought through how far the ID panels would extend. Looking at your 3-view drawing, I'd say that - to cover the roundels - they would have to go at least as far inboard as the aileron hinges.

The size of any of the red panels applied in the field would probably vary greatly from unit to unit. Factory-applied ID panels would be another matter. As rendered, the P.11's entire aileron hasn't been over-painted. If I had to pick a handy point, I'd say follow the panel lines just inboard of the hinges (which run all the way to the leading edge).